This invention relates to a pneumatic tire incorporating an integrated circuit transponder for use in tire identification and for the transmission of such tire data as temperature and pressure and the like. More particularly, the invention relates to the combination of a transponder and an electromagnetic coupling element and to the disposition of both within a tire.
For a century, the Goodyear Tire and Rubber Company of Akron Ohio, assignee of the present invention, has been the uncontested industry leader in tire product technology.
For example, as early as 1892, a puncture-resistant tire was patented. In 1934, a year recognized as the beginning of the runflat era, Goodyear introduced the Lifeguard (tm) safety tube, a fabric tube within the tire, used commercially by auto makers and on trucks. In 1993, Goodyear""s Eagle GS-C EMT (Extended Mobility Technology) won the Discover Award for Automotive Technological Innovation. In 1996, the Goodyear Eagle F1 runflat tire was chosen as standard equipment on the 1997 Chevrolet C-5 Corvette.
Other examples of the strides Goodyear has taken in the advancement of tire and related technologies include, but are not limited to, the following patented inventions:
Commonly-owned U.S. Pat. No. 3,665,387 (Enabnit; 1972), entitled SIGNALLING SYSTEM FOR LOW TIRE CONDITION ON A VEHICLE, incorporated in its entirety by reference herein, discloses a low tire pressure warning system adaptable for any number of wheels of a vehicle and providing dashboard indications of system operation and low pressure conditions while the vehicle is in motion.
Commonly-owned U.S. Pat. No. 3,831,161 (Enabnit; 1974), entitled FAIL-SAFE MONITORING APPARATUS, incorporated in its entirety by reference herein, discloses monitoring vehicle tire pressure wherein the operator is warned of an abnormal or unsafe condition of one or more of the tires.
Commonly-owned U.S. Pat. No. 3,872,424 (Enabnit; 1975), entitled APPARATUS AND METHOD FOR TRANSMITTING AUXILIARY SIGNALS ON EXISTING VEHICLE WIRING, incorporated in its entirety by reference herein, discloses communicating with low tire pressure monitoring circuits using power pulses carried on existing vehicle wiring (e.g., the turn signal circuits).
Commonly-owned U.S. Pat. No. 4,052,696 (Enabnit; 1977), entitled TIRE CONDITION MONITOR, incorporated in its entirety by reference herein, discloses a tire condition sensing circuit that includes a ferrite element that changes from a ferromagnetic to a non-ferromagnetic state in response to a temperature increase above the material""s Curie point.
Commonly-owned U.S. Pat. No. 4,099,157 (Enabnit; 1978), entitled SINGLE WIRE POWER/SIGNAL SYSTEM FOR VEHICLE AUXILIARY DEVICES, incorporated in its entirety by reference herein, discloses providing both power to and receiving detection signals from a remotely located condition monitoring device using a single wire with ground return through the vehicle frame.
Commonly-owned U.S. Pat. No. 4,108,701 (Stanley; 1978), entitled METHOD FOR MAKING HOSE INCORPORATING AN EMBEDDED STATIC GROUND CONDUCTOR, and related U.S. Pat. No. 4,168,198 (Stanley; 1979), entitled APPARATUS FOR MAKING HOSE INCORPORATING AN EMBEDDED STATIC GROUND CONDUCTOR, both incorporated in their entirety by reference herein.
Commonly-owned U.S. Pat. No. 4,911,217 (Dunn, et. al.; 1990), entitled INTEGRATED CIRCUIT TRANSPONDER IN A PNEUMATIC TIRE FOR TIRE IDENTIFICATION, incorporated in its entirety by reference herein, discloses an RF transponder in a pneumatic tire. FIG. 1a of this patent illustrates a prior-art identification system (xe2x80x9creaderxe2x80x9d) that can be used both to interrogate and provide energy to the transponder inside the tire. The identification system includes a portable hand-held module having within it an exciter and associated circuitry for indicating to a user the numerical identification of the tire/transponder in response to an interrogation signal.
Commonly-owned U.S. Pat. No. 5,181,975 (Pollack, et. al.; 1993), entitled INTEGRATED CIRCUIT TRANSPONDER WITH COIL ANTENNA IN A PNEUMATIC TIRE FOR USE IN TIRE IDENTIFICATION, incorporated in its entirety by reference herein, discloses a pneumatic tire having an integrated circuit (IC) transponder and pressure transducer. As described in this patent, in a tire that has already been manufactured, the transponder may be attached to an inner surface of the tire by means of a tire patch or other similar material or device.
Commonly-owned U.S. Pat. No. 5,218,861 (Brown, et al.; 1993), entitled PNEUMATIC TIRE HAVING AN INTEGRATED CIRCUIT TRANSPONDER AND PRESSURE TRANSDUCER, incorporated in its entirety by reference herein, discloses a pneumatic tire having an integrated circuit (IC) transponder and pressure transducer mounted within the pneumatic tire. Upon interrogation (polling) by an external RF signal provided by a xe2x80x9creaderxe2x80x9d, the transponder transmits tire identification and tire pressure data in digitally-coded form. The transponder is xe2x80x9cpassivexe2x80x9d in that it is not self-powered, but obtains its operating power from the externally-provided RF signal.
The commonly-owned U.S. Patents referenced immediately hereinabove are indicative of the long-standing, far-reaching and ongoing efforts being made by the Goodyear Tire and Rubber Company in advancing tire product technology. In particular, the lattermost patent, U.S. Pat. No. 5,218,861 (""861), describes xe2x80x9ca pneumatic truck tire having an integrated circuit transponder including an antenna coil which functions as a secondary winding coupled to the annular tensile member formed from steel wire and acting as a primary winding in the manner described above.xe2x80x9d The xe2x80x9cannular tensile memberxe2x80x9d referred to is specifically one of the tire""s two spaced-apart beads which is, in effect, used as the primary winding of a transformer whose secondary winding is the antenna coil of the transponder installed within the tire. U.S. Pat. No. 4,911,217, is referenced in the ""861 patent as utilizing this same sort of electric-field coupling (col. 5, 1. 10+).
The ""861 patent describes difficulties of incorporating the large-loop antennas of transponders into the tire manufacturing process wherein the tire must undergo a xe2x80x9cblow upxe2x80x9d from a cylindrical shape into the familiar toroidal shape of tires. The use of a small planar loop antenna, as the secondary winding of a transformer and one of the tire beads as the primary winding, enables the interrogation of a tire-mounted transponder from any position about the bead. Unfortunately, while the bead thus used enables easy communication between the transponder and the interrogator device when the tire is unmounted upon a metal wheelxe2x80x94the use of the bead as the primary winding is adversely influenced by the close proximity of the bead to the wheel when the tire is in use. In other words, the use of the tire bead as the primary winding in a magnetically coupled transponder system presents difficulties associated with the close proximity between the tire bead and the closely adjacent metallic wheel which presents the potential for interference with the RF communication between the transponder and the external interrogator which activates the transponder.
The present invention relates to a pneumatic radial ply runflat tire having a tread, a carcass comprising a radial ply structure having two or more plies, a belt structure comprising two or more belts located between the tread and the radial ply structure, an innerliner and two sidewalls each reinforced by one or more wedge inserts, and an electrically conductive and electrically continuous, single-turn hoop disposed radially inward of the tread and belt structure and radially outward of the carcass structure. The function of the hoop is that of a coupling element in a transformer comprising the hoop as the primary winding and the coil of a tire-mounted transponder as the secondary winding such that the tire-mounted transponder would have 360-degree readability about the circumference of the tire by a transponder interrogator that is external to the tire. The electrically continuous single-turn hoop has an electrical resistance about its circumference of preferably less than 10 ohms and is constructed of material resistant to fatigue and corrosion in the environment of an interior of a pneumatic tire. The electrically continuous single-turn hoop is more or less rectangular in cross section and is made from a solid band of electrically conductive material. Or the hoop can be made from a multiplicity of strands of electrically conductive material suitable to resist fatigue failure or of a single strand or wire of electrically conductive material that is non-rectangular in cross section. The plane of the hoop could contain the equatorial plane of the tire or it could lie on either side of the equatorial plane of the tire. The hoop could be disposed between any two of the two or more belts of the belt structure or radially outward of the belt structure and radially inward of the tread. Such a coupling element hoop is intended also to be used in conjunction with a tire-mounted transponder within a tire that is not designed for runflat operation.
The transponder coupling-element hoop of the present invention is intended for use in tires having a belt structure having two laterally spaced apart sides that are disposed more or less symmetrically with respect to each other about the equatorial plane of the tire. More specifically, the electrically conductive and electrically continuous single-turn hoop would be disposed radially inward of the tread and between the two laterally spaced apart portions of the belt structure. The hoop would have the above described properties of cross-sectional shape and solid or stranded structure and an electrical resistance about the circumference of the tire of preferably less than 10 ohms.
The invention contemplates yet further the use of a tread-supporting structural hoop in the role of a primary winding in a coupling-element transformer allowing 360-degree readability of a tire-mounted transponder. Such a structural hoop would have the above described electrical properties of a single-turn, electrically continuous loop having an electrical resistance of preferably less than 10 ohms about the circumference of the tire.
Other benefits and advantages of the invention will become apparent to those skilled in the art to which it pertains upon a reading and understanding of the following detailed specification.